This weekend, we observe World Tuberculosis (TB) Day (Sunday, March 24), a day to remember that the global burden of TB remains enormous, particularly among people with HIV/AIDS, among whom TB is the leading cause of death, worldwide. According to the World Health Organization (WHO), in 2011, 1.4 million people died from TB, including 430,000 deaths among people who were HIV-positive. TB is also one of the top killers of women around the globe, with 300,000 deaths among HIV-negative women and 200,000 deaths among HIV-positive women in 2011.

TB is also a health threat among people living with HIV in the United States. In 2011, the Centers for Disease Control and Prevention (CDC) estimates that 6% of all TB cases in the U.S. and 10% of TB cases among people aged 25–44 occurred among people who are living with HIV.

Thankfully, the rate of TB is declining in the U.S. According to the CDC, the number of TB cases reported annually has decreased since its peak in 1992. In addition, most cases of TB disease in the U.S. now occur among immigrants; in 2011, a total of 62% of reported TB cases in the United States occurred in foreign-born persons (CDC). (Read more about TB trends in the U.S. in the March 22, 2013 issue of CDC’s Morbidity and Mortality Weekly Report (MMWR).)

However, tuberculosis remains a serious concern for people living with HIV/AIDS. That’s because a dangerous synergy exists between HIV and TB, such that people who have a suppressed immune system due to HIV infection are much more likely to develop active TB disease if they are exposed to the TB bacteria. Also, active TB infection appears to increase HIV replication among co-infected persons. Therefore, the populations of people who are infected with these two pathogens often overlap. Or, as an historical leader in the field of HIV (Dr. Jim Curran) once observed: “HIV and TB hang out together and they are a bad influence on each other!”

In addition, while TB is curable with proper treatment, erratic or improper treatment can lead to drug resistance—one of the most serious problems facing people living with HIV who are coinfected with TB. Multidrug-resistant TB (MDR TB) is an extremely difficult to-treat and potentially fatal form of TB that is resistant to at least two of the best anti-TB drugs, isoniazid and rifampin. In addition, Extensively Drug-Resistant Tuberculosis (XDR TB) is rare type of MDR TB that is resistant to both the most powerful first-line drugs as well as to one of three second-line drugs. People living with HIV or AIDS are at greater risk of dying of MDR TB and XDR TB.

If you are an individual living with HIV, be sure to talk to your healthcare provider about tuberculosis and make sure you’ve been tested for TB. CDC recommends that all people who are newly diagnosed with HIV infection should be tested for TB as soon as possible, regardless of their TB risk category. In addition, people living with HIV who remain in a “high risk” category for repeated or ongoing TB exposure should be tested annually to find out if they have latent TB infection (LTBI). This includes individuals who have been incarcerated, those who live in group settings such as shelters or rehabilitation facilities, people who are active drug users, and those who have other risk factors for TB. People who are HIV-positive and who have a positive diagnostic test for LTBI should undergo additional clinical tests to rule out active TB disease.

For those of you who are interested in the most recent scientific advances, the Conference on Retroviruses and Opportunistic Infections (CROI), held earlier this month, featured several sessions on TB and the challenges it poses to those living with HIV. The symposium “TB on the Verge” discussed the challenges of HIV-related TB and new approaches for the treatment of MDR TB. Researchers on TB and clinical care discussed recent advances in targeted TB prevention therapy and community-wide and combination prevention strategies; the changing TB diagnostic landscape; the treatment of TB in HIV-infected pregnant women and children; and the current state of MDR TB treatment. The webcast of this CROI symposium is available online.

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